The Hatha Yoga Pradipika is a classic manual on Hatha Yoga, written by Yogi Svatmarama (15th century CE), a sadhu belonging to Gorakh panth. Said to be the oldest surviving text on the Hatha Yoga, it is one of the three classic texts of Hatha Yoga, the other two being the Gheranda Samhita and the Shiva Samhita.
This book is divided into four chapters (called Upadeshas). In chapter 1, Svatmarama describes fifteen asanas, and recommends dietary habits. In chapter 2, he establishes the connections between breath, mind, life, nadis, and prana, then describes the six karmas and the eight kumbhakas. In chapter 3, Svatmarama says what mudras are for, then describes the ten mudras. In chapter 4, he discusses samadhi, laya, nada, two mudras, and the four stages of Yoga.
It is dedicated to Lord Adinath (Lord Shiva) who is believed to have imparted the secret of Hatha Yoga to his divine consort Parvati.
Eight Sample Verses excerpted from this book:
1. Yoga succeeds by these six: enthusiasm, openness, courage, knowledge of the truth, determination, and solitude.
2. Success is achieved neither by wearing the right clothes nor by talking about it. Practice alone brings success. This is the truth, without a doubt.
3. When the breath is unsteady, the mind is unsteady. When the breath is steady, the mind is steady, and the yogi becomes steady. Therefore one should restrain the breath.
4. As salt and water become one when mixed, so the unity of self and mind is called samadhi.
5. He who binds the breath, binds the mind. He who binds the mind, binds the breath.
6. Center the self in space and space in the self. Make everything space, then don't think of anything.
7. Empty within, empty without, empty like a pot in space. Full within, full without, full like a pot in the ocean.
8. Don't think of external things and don't think of internal things. Abandon all thoughts, then don't think of anything.